[You must be registered and logged in to see this image.]THE blacked-out slits in the rear door of the Nissan Leaf are the first clue that there is something different about this particular battery-electric car. But the words “Autonomous Drive” stencilled across its sides are more of a giveaway.

Earlier this week, Nissan, Japan’s second-largest carmaker, became the first manufacturer to announce plans to put a driverless car into production. Andy Palmer, the firm’s executive vice president, expects it will roll down an assembly plant by 2020. Just as significantly, it hopes to offer autonomous driving capabilities on all of its models within the following decade.

Autonomous driving will reduce accidents and improve safety, reckons Mr Palmer, perhaps even ending road-traffic fatalities altogether. The technology should also allow more efficient use of public roads, especially in traffic-snarled cities, reducing energy consumption as vehicles have to stop-and-go less frequently. Mr Palmer estimates the technology could cut CO2 emissions from cars by as much as 300m tonnes a year worldwide.

Nissan is by no means the only firm interested in autonomous driving. Virtually every carmaker is now experimenting with the concept, as is Google which has logged many thousands of miles with its own prototypes. Indeed, Google has been perhaps the most ambitious proponent. It thinks it could be ready to partner with an established automaker by 2017, although industry-watchers think the middle of the next decade is more realistic.

Many of the underlying technologies, including cameras, laser, radar and sonar sensors and heavy-duty microprocessing power are already found on production models. The 2014 Mercedes-Benz S-Class features what the German maker describes as a “sensor fusion”, bringing together various systems designed to detect obstacles, traffic and even read road signs. It can, for example, automatically stop if a pedestrian walks out in front of it, and its “magic” suspension uses a camera to help smooth out bumps and ruts.

But the challenge of bringing all the technology together to create a fully autonomous car is daunting. In a simulation for reporters in Los Angeles, at an event dubbed Nissan 360, the autonomous Leaf prototype effortlessly merged into traffic and then manoeuvred around a length of orange barrels. On an urban track it weaved around a figure-of-eight course, slowing to accommodate oncoming traffic as it squeezed around another car parked partially in its lane. It then waited at a stop sign for crossing traffic to clear. The real world will be tougher to manoeuvre, however. Human drivers must constantly adapt to obstacles and unexpected conditions. “We need to be able to drive any intersection anywhere and at any time to be fully autonomous,” says Maarten Sierhuis, the project’s co-director.

This means Nissan’s target date might be ambitious. And there are other obstacles beyond construction sites and speed bumps to overcome. America may be tech-friendly but it is also highly litigious. Attorneys, one suspects, are eagerly awaiting the first crash involving an autonomous vehicle to create a new line of legal work that could keep them as busy as the engineers developing the technology. Nissan says that regulations need to be made more friendly before driverless cars go on sale. The battle must be won in politicians’ lobbies, before it is waged on forecourts.